The O-ring on the solid rocket booster did not expand enough during the launch due to the outside temperatures being to cold and ultimately conbustible material leaked and ignited the fuel causing a mass explosion
Challenger Disaster.
The space shuttle Challenger lifted off on January 28, 1986 at 11:38:00 a.m. EST. Seventy three seconds into the mission, Challenger exploded, killing the entire crew of seven,...
Challenger exploded over the Atlantic Ocean off the coat of Florida, not far downrange from the Kennedy Space Center where it had launched only 73 seconds earlier
Liftoff was at 11:38:00.010 Eastern Standard Time. The O-ring failure developed almost immediately, leading to the explosion and breaking apart of the shuttle 73 seconds into the flight.